That list can be sorted by Fit the smallest are the PicoAlt PICO-P1 and the Adrel BMP, the first fits a 12mm tube (BT-5) and the second a 13mm tube, the prices have probably increased a bit from $40 and $55. There may be other newer ones that will fit small airframes but those are the smallest two listed.

My attempt to simplify it resulted in an extensive list of all currently available model rocket altimeters and their parameters, such as dimensions, weight, sensors being used, interfaces, pyro options, battery and voltage requirements, etc. All data was compiled from vendor datasheets and manuals. If it's something TRF community finds useful, I'd keep maintaining it.

Now here's how you could help: I'm missing some data for few altimeters (look for question marks), mostly related to dimensions and recording functions. If you have one, measure it / post a file with a recorded flight, and I'll update the guide accordingly.

Second, the long-advertised external data display device for the PerfectFlite FireFly is now real and available. It provides a means to read apogee, peak speed, time to apogee, total flight time, descent rate, and battery voltage of both the display unit itself and the FireFly via an LCD display. Here's the display unit: http://www.perfectflitedirect.com/fi...-data-display/ I have one and it works actually quite nicely. Oddly, it's not yet on the regular PerfectFlite site. Maybe a notation over in the OS column for the FireFly would be where you'd mention this, since it's not essential to use the unit as a peak-reading altimeter. Or maybe an addition to the "Click!" notation in the "Record" column. Whatever works best for keeping things consistent.

Finally, the NAR has recently revised the list of altimeters accepted for competition use, and the list is much shorter than before. The current list is here: http://www.nar.org/contest-flying/us...r-contest-use/ So....some of the check marks to remove from the "competition" column.

One data point that might be worth adding - support for staged rockets - my emails to @John Bean last week confirmed that the Altimeter3 will likely not understand a multi staged rocket... Given he's on the thread, he might be able to expand...

Reasonably new to rocketry and hailing from the land down under.. I speak metric... I know not of these feet and inches you speak of...

I think the all time smallest baro dual deploy was the Pico unit but I suspect Robert Dehate is not selling them anymore. It will fit in just about any modroc but............ and I do mean but.............. Trying to get all the pieces into a small space is
challenging and a setup interface has to be cobbled together and is not easy to change. There are also several wiring schemes suggested that would be confusing to a neophyte. Kurt

One data point that might be worth adding - support for staged rockets - my emails to @John Bean last week confirmed that the Altimeter3 will likely not understand a multi staged rocket... Given he's on the thread, he might be able to expand...

Like AltimeterTwo, AltimeterThree expects one engine, so that's what it will report (and while some stats like apogee will be fine, othersólike max speedómay not). The second engine will be ignored, or in rare cases may fool the ejection detection and muck up some of the timing stats and the ejection altitude.

With a slight tweak to software, we could add "2 Stage Analysis." That would lengthen the list of stats shown in the app, and add a stat for interstage coast. Max speed would continue to be calculated and would presumably occur during second stage boost.

A stat for calculating Cd (decel * velocity^2) has also been requested.

With a slight tweak to software, we could add "2 Stage Analysis." That would lengthen the list of stats shown in the app, and add a stat for interstage coast. Max speed would continue to be calculated and would presumably occur during second stage boost.

consider this my formal RFE (Request For Enhancement)!!

Reasonably new to rocketry and hailing from the land down under.. I speak metric... I know not of these feet and inches you speak of...